Boone, Echinodermata, Cruises of "Ara" and "Alva" 185 



protruberances in which are embedded numerous tabular deposits, 

 the spires of these tables rendering the surface of the integument 

 rough. The collar near the margin has numerous robust papillae 

 which are slightly smaller than the above described protruber- 

 ances. In the ventral surface the pedicels are numerous, arranged 

 in three longitudinal bands, the median of which is about twice 

 as wide as either lateral band. On the dorsal surface the papillae 

 are scattered, there being four irregular approximate longitudinal 

 series of very coarse protruberances, namely, one each on both 

 dorsal ambulacra and one very irregular series on either side 

 adjacent to the ventral surface. The apex of the verrucae each 

 terminate in a papilla. Smaller papillae are scattered over the 

 interambulacra, about 5 to 10 millimeters apart. 



The deposits consist of four types: (a) Large, stout tables 

 with a broad basal disk of irregular margin and having one di- 

 ameter longer than the other; this disk being perforate with 

 irregular shape, subcircular to suboval holes of various sizes ; the 

 disk supports a well developed tapering spire, with two or three 

 cross pieces and terminating in a single or, more rarely, two or 

 three points, (b) The smaller tables are found in both dorsal 

 and ventral peristome and are about one-half of a millimeter high. 

 They are of varying size. The disk is small, subquadrate with 

 irregular marginal contour, usually four peripheral large holes 

 at the base of the spire supports and with a truncate spire, ter- 

 minating in 8 to 16 small, sharp teeth, (c) The third type of tables 

 is similar to the second but is larger and has a much higher spire, 

 also more numerous perforations near the circumference of the 

 disk. The third type of deposit consists of dichotomously 

 branched rods, forming small, somewhat imperfect rosettes, 

 scarcely a half of a millimeter long, abundant in the dorsal peri- 

 stome but rare in the ventral, (d) The fourth type of deposits is 

 the small C-shaped bodies, from 0.1 to 0.2 millimeters long, scat- 

 tered throughout the entire integument. 



The calcareous ring is well developed in the present specimen 

 and has the radial pieces decidedly larger than the interradial; 

 anteriorly the border has four blunt points, posteriorly, two longer 

 ones. Each radial piece has a single point anteriorly and pos- 

 teriorly the margin is concave. 



Two Polian vesicles are present, normally developed. The 

 madreporic canal is single, situated in the dorsal mesentery. 



